The sum of number of lone pairs of electrons present on the central atoms of $$XeO_3$$, $$XeOF_4$$ and $$XeF_6$$ is ______.

We need to find the sum of the number of lone pairs on the central atoms of $$XeO_3$$, $$XeOF_4$$, and $$XeF_6$$.

Analyze $$XeO_3$$

Xe is the central atom. Xe has 8 valence electrons. It forms 3 double bonds with oxygen (uses 6 electrons).

Remaining electrons on Xe = 8 - 6 = 2, which gives 1 lone pair.

Geometry: Trigonal pyramidal (sp$$^3$$ hybridization).

Analyze $$XeOF_4$$

Xe has 8 valence electrons. It forms 4 single bonds with F (uses 4 electrons) and 1 double bond with O (uses 2 electrons).

Remaining electrons on Xe = 8 - 6 = 2, which gives 1 lone pair.

Geometry: Square pyramidal with one lone pair (sp$$^3$$d$$^2$$ hybridization).

Analyze $$XeF_6$$

Xe has 8 valence electrons. It forms 6 single bonds with F (uses 6 electrons).

Remaining electrons on Xe = 8 - 6 = 2, which gives 1 lone pair.

Geometry: Distorted octahedral (sp$$^3$$d$$^3$$ hybridization).

Calculate the sum

$$\text{Total lone pairs} = 1 + 1 + 1 = 3$$

The answer is 3.